This invention relates to a device suitable for preparing by kneading a calcium phosphate-based cement which may be utilized as a dental or medical cement and for applying the resultant kneaded cement to a treatment site, and to a method for preparing a calcium phosphate-based cement. More particularly, the invention relates to a kneading device for preparing calcium phosphate-based cement and for applying the resultant kneaded cement to defective portions of bone, for example bone which has suffered fracture or osteoporosis, or applying the resultant kneaded cement as an adhesive for bonding artificial bone, such as that formed from metal or ceramic, to bone, as well as to a method for preparing the calcium phosphate-based cement.
Calcium phosphate-based cement, which contains a predominant amount of calcium phosphate, is identical to the inorganic component of bones or teeth. Calcium phosphate-based cement therefore exhibits high bio-compatibility and is useful in certain fields of medical treatment, such as orthopedics and anaplasty. Such calcium phosphate-based cement is conventionally prepared by mixing calcium phosphate powder and a kneading liquid, such as distilled water, for example, in a mortar to obtain kneaded cement which may then be filled into or applied to a defective portion of bone or tooth using a syringe or spatula and then allowed to cure.
However, the whole procedure involves strenuous labor in kneading whether performed manually or with motor assistance and in introducing the kneaded cement into a syringe. Further, foreign matter or unwanted bacteria may enter the cement during the course of kneading or of introduction into the syringe.
An object of the present invention is to solve the above problems encountered in the conventional procedure and to provide a kneading device for calcium phosphate-based cement which facilitates kneading and is capable of preventing entry of foreign matter or unwanted bacteria into the cement being kneaded, as well as to provide a method for preparing and applying calcium phosphate-based cement.
The kneading device according to the invention suitable for preparing calcium phosphate-based cement comprises: a cylinder, which includes a hollow cylindrical body portion and a nozzle formed at the distal end of the cylindrical body portion; a plug including an axial through-hole slidably disposed within the cylindrical body portion; a piston assembly which includes a shaft extending through the through-hole of the plug for axial and rotatable movement, a kneading element at the distal end of the shaft within the cylindrical body portion and a handle formed at the proximal end of the shaft external of the cylindrical body portion; a cover member attached to and forming a closure for the nozzle; and a stop member for locating the plug in position at the proximal end of the cylindrical body portion.
The method according to the present invention for preparing calcium phosphate-based cement comprises the steps of: introducing calcium phosphate-based cement and a kneading liquid into the hollow interior space defined by the cylinder and the plug of the kneading device described above; subjecting the piston to axial and rotary movement relative to the cylinder thereby to knead the calcium phosphate-based cement and the kneading liquid into kneaded cement; retracting the piston assembly such that the kneading element contacts the plug; detaching the cover member and the stop member; and moving the piston assembly towards the nozzle so as to extrude the kneaded cement from the cylinder through the nozzle.